app.js

require('jimi').run({
    url_conf: require('./urls')
});

handlers.js

var jimi = require('jimi');

exports.hello_world = function (req, res) {
    jimi.respond(res, 'Hello World');
}

urls.js

var handlers = require('./handlers');

exports.mappings = [
    ['^$', handlers.hello_world]
];